Portable electronic devices such as cellular telephones, personal digital assistants (PDAs), wireless email devices, instant messaging devices, pagers, portable compact disk (CD) players, portable MP3 players, and others are often forgotten, lost, or stolen (a “PED” includes any portable device that can be used for communication, performing intellectual and/or physical work, and/or entertainment). Existing wireless device loss detection approaches focus primarily on remotely accessing a device after it is lost. This allows prohibiting the device, such as a cell phone, from placing phone calls. It also allows hiding the device owner's information or erasure of sensitive data. This strategy aims to increase the user's chances of recovering the device and to protect data stored in the device. This method does not allow users to quickly recover their lost devices. Other methods for tracking and locating a lost cell phone include network triangulation and GPS interrogation. These methods do not allow users to automatically and/or instantaneously recover their lost devices. Another method and apparatus for reducing the likelihood of losing a portable electronic device is disclosed in U.S. Pat. No. 6,836,212, and in U.S. Pat. No.7,005,999, which monitors inadvertent removal of a portable electronic device (PED) from its retaining device. So, if the PED is already removed from its retaining device for use or the retaining device and PED are left behind together or move out of a desired range, this apparatus does not protect users from losing their PEDS.
U.S. Patent application publication 20050280546 discloses two mobile transceivers that are linked through a Bluetooth link. The Bluetooth enabled RF link between the first and second mobile transceiver units forms a monitoring piconet. The second mobile transceiver unit provides an alarm indication when the first mobile transceiver unit moves beyond a distance of approximately ten meters from the second mobile transceiver unit. The second device repeatedly pages the first device, and waits for a response. If a response is not received, an alarm is issued. This system is unreliable and unfit for use as a proximity alarm because paging consumes 40 mA, a rate that would inconvenience the user by requiring an expensive and/or heavy battery or frequent recharging. Further, paging is often blocked by human bodies, which can result in false alarms when a page does not reach the first device. Nevertheless, a Bluetooth based communication system has many benefits over traditional analog systems, including greater security and the ease of designing and building transceiver systems using Bluetooth. Due to the widespread acceptance and use of the Bluetooth standard, circuitry for Bluetooth systems has been built into small, lightweight chips, which are readily available at low cost.
U.S. Pat. No. 6,885,848 is directed to an apparatus for preventing the loss of a portable telephone that uses Bluetooth communication protocol. The signal strength is periodically monitored and an alarm issued to the headphone when the signal is below a threshold. Bluetooth protocol provides for a received signal strength indicator (RSSI) value or the Link Quality value to be determined at any time. If the value received is below a threshold, an alarm is issued to the headphone. This system and method have been tested, and not found to a reliable way for indicating that a mobile phone has left a proximity range due to production of false positives. Further, the system requires that the headphone be proximate an ear for the alarm to be detected.
U.S. Patent application publication 20020080036 discloses the use of a mobile network for tracking the position of a plurality of objects and displaying them on a map; the apparatus in this patent requires expensive transceivers, and has a significant time delay for indicating object is out of range.
U.S. Pat. No. 6,989,748 discloses a battery with an integrated tracking device. The system is difficult to commercialize because of the large variety of batteries on the market. Furthermore, the transmitter/receiver system needs an antenna, and it would be a challenge to install an antenna inside the battery or on its surface as that would compromise its performance.
U.S. Pat. No. 7,002,473 discloses a loss prevention system that uses RFID. It requires a bulky transceiver that interrogates all the RFID tags. It is not convenient for portable applications inter alia.
U.S. Pat. No. 5,796,338 discloses a system and method for preventing loss of a cellular phone or similar portable device. The system includes a wireless transmitter in cell phones for intermittently sending security signals to a pager worn by the user. An alarm is actuated when the strength of the security signal falls below a predetermined threshold. This system cannot be used with existing phones and requires cell phone manufacturers to modify their designs.
In general, there exists a need for technologies that enable one to know that certain persons, animals or things (e.g., mobile phones, and computers) stay within a desired proximity of a specified area. For example, a parent in a shopping mall may want their child to stay within a certain proximity of the parent and may wish to remotely monitor the child's activities; should the child go beyond the desired proximity it is desired that a clear notice be given (e.g., alarm requiring acknowledgement) and perhaps even communicate with the child. Another example is that a parent walking in a park may want their walking child to stay within a certain range. Or a person walking their dog wants it to stay within a certain range. With respect to things, people generally want their mobile phone and/or portable computers or other PEDs to stay within a certain range to avoid loss thereof and/or unauthorized access or to have them at hand for use.
In order to solve these problems, there is a need for technologies that are simple to use, inexpensive to build and use, small and light weight enough to be mobile, adaptable for different situations, and secure.
However, such an analog RF system is capable of being undermined by other interfering devices. While the manufacturer may vary the signal frequency used by different pairs of transmitters and receivers, it is possible for a receiver in a first pair to detect a transmitter from a second pair, thus risking the possibility that the first receiver would not detect the first transmitter going out of range, which could not only mean that a child being monitored goes out of range without an alarm but that the parents would have a false sense of security that the child was within range and so consequently they do not look after the child as much they may otherwise have without the system. This derives from the system being designed to work at a common pre-set frequency between the transmitter and receiver, and the receiver cannot discriminate between different transmitters transmitting at substantially the same frequency. Further, when a transmitter or receiver is lost, it is not likely that a replacement can be readily obtained that has a matching fixed frequency transmission or reception range, despite the possibility of an interfering transmitter being encountered at random in use. The lack of security on these RF type transmitter receiver pairs means that a child or pet abductor can monitor the frequency of a first transmitter and program a second transmitter that can be used as a decoy to defeat the system. While an analog transmitter and receiver can be preset to be a pair, i.e., one can receive the signal of the other automatically when within range, this should not be confused with the process of pairing of two digital devices that also use RF type communication. For example, Bluetooth headset devices are available that pair with a mobile phone. A Bluetooth headset can provide a tone to the ear of a wearer when the Bluetooth connection to the mobile phone is dropped. However, one must be generally within about 3 feet of the headset to hear the tone if the mobile phone is moved out of range of the headset.
Thus, a need exists for systems for monitoring persons, things, and animals that are reliable, simple to use, cost effective, mobile, adaptable and secure. Such systems should provide an alarm to users upon detecting that a person, animal or thing is not within a desired proximity, wherein the alarm is appropriate to the circumstances. Further, there is also a need for more proactive systems to reduce the risk of loss of a person, animal or thing, and to make such systems ubiquitous as standard accessories.